1. Field of the Invention
The present invention relates to devices for the detection of fluorescent substances on the surface of the earth.
2. Description of the Prior Art
A device capable of detecting fluorescent substances on the earth's surface is disclosed in a publication by Scintrex, 222 Snidecroft Raod, Concord, Ontario, Canada, dated Oct. 1, 1982. The device is installed in a helicopter and comprises a laser that emits a narrow beam illuminating a limited spot on the surface of the earth. The means for detecting fluorescence comprise an optical system aimed at the illuminated spot. This publication also describes a hand held device of the same type. Whenthis prior art device is used with a helicopter, the distance of the helicopter from the surface of the earth, the helicopter's flying speed, the frequency of the laser (i.e., number of pulses emitted per second), and the size of the illuminated surface area permit the investigation of only very small points. Furthermore, coordination of the surface area sampled from the helicopter with a map is extremely difficult, and requires time-consuming subsequent investigation on the ground. Similarly, the hand held instrument can only illuminate a few square centimeters at a time. Thus, neither of these Scintrex devices is suitable for the exploration of large surface areas on the ground.